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We examined the effects of vegetation, vegetation density, and veg location on overall delta and channel dynamics. We conducted a series of experiments with a variety of seeding styles, including 1 unvegetated control run. Experiments were all conducted under the same water and sediment input conditions, with vegetation as the only variable.

We conducted a series of experiments at the University of Texas at Austin to discover the effect of a mobile substrate on an evolving delta. All of the runs had constant sediment supply, water supply, and base level, but varied mobile substrate thicknesses.

We present the results of an experimental study of topography dynamics under conditions of constant precipitation and uplift rate. The experiment is designed to develop a complete drainage network by the growth and propagation of erosion instabilities in response to tectonic perturbations. The quantitative analysis of topographic evolution is made possible by using telemetric lasers that perform elevation measurements at an excellent level of precision. We focus our study on the effect of initial surface organization and of uplift rate on both the transient dynamics and the steady state forms of topography. We show that the transient phase is strongly dependent on the initial internally drained area, which is found to decrease exponentially with time. The topography always reaches a steady state whose mean elevation depends linearly on uplift rate with a strictly positive value when uplift is zero. Steady state surfaces are characterized by a well-defined slope–area power law with a constant exponent of 0.12 and an amplitude that depends linearly on uplift rate with a strictly positive value when uplift is zero. These results are consistent with a stream power law erosion model that includes a nonnegligible threshold for particle detachment. Uncertainty regarding the sediment transport length is resolved by calibrating the transient dynamics with a surface process model. Reappraising published results on the linear dependency between mean elevation, or relief, and denudation rate, we suggest that an erosion threshold is worth considering for large-scale systems.

Boundary forces generated by debris flows can be powerful enough to erode bedrock and cause considerable damage to infrastructure during runout. Formulation of an erosion-rate law for debris flows is therefore a high priority, and it makes sense to build such a law around laboratory experiments. We scale up granular impact forces by running our experiments under enhanced gravity in a geotechnical centrifuge. Using a 40cm-diameter rotating drum spun at up to 100g, we generate debris flows with an effective depth of over several meters. By varying effective gravity from 1g to 100g we explore the scaling of granular flow forces and the consequent bed and wall erosion rates. The velocity and density structure of these granular flows is monitored using laser sheets, high-speed video, and particle tracking, and the progressive erosion of the boundary surfaces is measured by laser scanning.